I've been thinking on this plot-point that get's used in fantasy & science-fiction games and some literature series. Take for example, the Reapers from Mass Effect.

Here we are with an incredibly interesting universe where humanity is making it's very first steps out into the stars, where it's meeting other life-forms, developing it's own advanced tech, there are all these different and varied cultures and worlds to interact with, like the Batarians in the Terminus Systems or Aria and Omega or Moridin and his people's faith. You've got characters like Wrex, Tali, and Miranda, each unique in their backstory, their people's sufferings and beliefs, etc...

And the primary plot of the story is to fight back against these millennia-old Artificial AI that apparently genocide synthetics and organics every "cycle" for some vague reasoning. I don't know, I never went past Mass Effect 1.

Same thing with say, Game of Thrones. Very interesting series starting out primarily with an incredible amount of political intrigue, military conflicts and characters growing and becoming great in this intricate web of lives, and it feels like it's all just build-up for this climactic war with Others or Melisandre's Fire God or whatever.

Starcraft (Dark Voice & Hybrid)? Star Wars (Jedi & Sith)? Assassin's Creed (the 2012 Juno threat)? Halo (Covenant, Flood, Didact, etc...)? World of Warcraft?

I don't know, I just feel like it's a hindrance or handicap to universes that could do so much more with their stories than fight an ultimate evil or whatever.

 

With Mass Effect, I feel that the depth of the world you described is what makes the Reapers a good enemy -- the threat of all that work and the achievements every species has performed being wiped away raises the stakes quite a bit. These stories about impending apocalypses need this build-up to make you care and give the threat credibility.

Now, the problem in Mass Effect is the lack of an expanded universe, to show the things going on besides what Shepard sees directly. Instead we get the badly written and drawn trash Bioware has Dark Horse produce that means nothing and in a lot of cases worsens rather than improves the ME franchise.